1. Field of the Invention
The present invention relates to a fan drive attachment assembly for a motor vehicle.
2. Description of the Prior Art
Current fan drive attachment assemblies in motor vehicles, such as for a water pump or a fan drive bearing assembly, use a drive hub with a cylindrical drive shank and fan drive with a fan shaft. The fan shaft and drive shank are designed to frictionally fit together, generally through screwing the drive shank into a cylindrical axial bore in the fan shaft.
Unfortunately the drive shank and fan shaft easily misalign, causing the drive hub and fan drive to misalign. Any misalignment between the drive hub and the fan drive can generate excessive shaking forces while the fan is running. This shaking reduces the life of the fan drive or the fan drive bearing.
There are two different ways the drive shank and fan hub misalign. The first way to misalign is radial runout. Radial alignment of the fan drive with the drive hub is typically controlled by a threaded engagement between the drive shank and the fan shaft. Thread clearance can allow parallel alignment of the drive hub and the fan drive to be parallel, but not on the same axial line.
The second type of misalignment is axial misalignment. Current fan drive attachment assemblies require the mounting faces of the drive hub and fan drive to be parallel to the centerline of the drive hub and the fan drive. Machining error, debris, such as paint, rust, and the like, can cause angular misalignment of the fan drive as it is installed. Misthreading during insertion could also cause an angular misalignment.
Therefore, it would be advantageous to design a fan drive attachment assembly to reduce the possibility of misalignment of the drive hub and fan drive, yet is easy to assemble.